None.
This invention relates generally to railroad trackwork switches, and particularly concerns sensor apparatus useful for detecting and indicating whether or not the switch point of a railroad trackwork switch is satisfactorily positioned with respect to the switch stock rail.
Railroad trackwork hand-thrown switches conventionally make use of an electro-mechanical switch status circuit controller for the detection of the position of a switch point relative to the switch stock rail, and since the operation of such controller relies upon mechanical hardware connected to the rail it accordingly is subject in the course of railroad operations to mechanical damage and to the effects of temperature variations. The use of proximity sensing techniques and hardware in lieu of the state-of-the-art electro-mechanical control approach, if properly done, offers the potential of eliminating the mechanical damage and temperature variation short-comings associated with present railroad operations.
Accordingly, it is a principal object of the present invention to provide proximity sensing hardware that reliably indicates the operating status (i.e., xe2x80x9ceither satisfactoryxe2x80x9d switch closure or xe2x80x9cunsatisfactoryxe2x80x9d switch closure) of a connected hand-thrown railroad trackwork switch.
Another object of the present invention is to provide proximity sensing hardware that is not adversely affected by temperature variations encountered in trackage in connection with typical railroad operations.
A still further object of the present invention is to provide proximity sensing hardware that is not xe2x80x9cfooledxe2x80x9d by the presence of stray metal or other detritus in the co-operating railroad trackwork switch assembly.
Another object of the present invention is to provide proximity sensing hardware for a railroad trackwork switch that may be conveniently maintained in the course of normal railroad operations. Other objects of the present invention will become apparent during consideration of the detailed description, drawings, and claims which follow.
The railroad trackwork switch assembly of the present invention is essentially comprised of a relatively fixed conventional stock rail, a conventional switch point that is relatively movable into and out of abutting engagement with the switch stock rail, a dual target magnetic field source array sub-assembly affixed to the switch point, a control box element containing dual Hall-effect sensor arrays and affixed to the switch stock rail, and electrical/electronic circuitry contained in the control box element and properly interconnecting the invention dual target magnetic field source array and dual Hall-effect sensor array elements with a power source and an external switch closure status condition signal generator.
The apparatus functions to generate a xe2x80x9ctruexe2x80x9d control signal when the switch point is in a properly closed condition, and a xe2x80x9cfalsexe2x80x9d control signal whenever the switch point is unsatisfactorily positioned relative to the switch stock rail for a closed switch condition. The xe2x80x9cfalsexe2x80x9d control signal causes the external switch closure condition signal generator to display an observable condition indicator (e.g., a red light) meaning that applicable railroad operating restrictions are in effect.
FIG. 1 is a schematic perspective view of a portion of a railroad trackwork switch illustrating the switch stock rail, switch point, and a preferred embodiment of the present invention incorporated therein;
FIG. 2 is a section view taken at line 2xe2x80x942 of FIG. 1;
FIG. 3 is a perspective view of the dual target sub-assembly of the present invention;
FIG. 4 is schematic view of the xe2x80x9cengagedxe2x80x9d positioning of an invention sensor array element relative to an invention target magnetic field source array element;
FIGS. 5, 6, and 7 schematically illustrate various registration and non-registration conditions of an invention sensor array element relative to an invention target magnetic field source array element;
FIG. 8 is a front elevation view of the control box element of FIGS. 1 and 2 with the control box cover plate removed;
FIG. 9 is a rear elevation view of the control box element of the present invention illustrating the positioning of the invention dual sensor array elements;
FIG. 10 is a schematic functional block diagram of the invention control box element and signal display, in totality; and
FIGS. 11A, 11B, and 11C comprise a schematic flow diagram of the program for the microprocessor portion of the invention electrical/electronic circuitry element.